Display device

ABSTRACT

According to one embodiment, a liquid crystal display device includes an array substrate, a counter-substrate, a negative liquid crystal layer including liquid crystal molecules, a retardation film attached to a surface of the array substrate, a first polarizer attached to the retardation film and having a first absorption axis, a second polarizer attached to a surface of the counter-substrate, and having a second absorption axis which is parallel to a direction of initial alignment of the liquid crystal molecules and perpendicular to the first absorption axis, a cover member located opposite to the second polarizer, and ultraviolet curing resin which bonds the second polarizer and the cover member to each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityunder 35 U.S.C. § 120 from U.S. application Ser. No. 15/847,031 filedDec. 19, 2017, which is a continuation of application Ser. No.14/838,573 filed Aug. 28, 2015 (now U.S. Pat. No. 9,874,781 issued Jan.23, 2018), and claims the benefit of priority under 35 U.S.C. § 119 fromJapanese Patent Application No. 2014-177030 filed Sep. 1, 2014, theentire contents of each of which are incorporated herein by reference.

FIELD

Embodiments described herein relate generally to a liquid crystaldisplay device.

BACKGROUND

In recent years, a study has been made of liquid crystal display devicesin which a displayed image can be viewed even by a user wearingpolarized sunglasses. As such a liquid crystal display device supportinguse of polarized sunglasses, a liquid crystal display is disclosed inwhich of protective films included in a polarizing member disposed on adisplay surface of a liquid crystal display panel, a protective filmdisposed on a display surface side has a phase-difference value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically showing an equivalent circuit and aconfiguration of a liquid crystal display panel PNL included in a liquidcrystal display device according to an embodiment.

FIG. 2 is a schematic plan view showing a configuration example ofpixels in an array substrate AR as shown in FIG. 1, as viewed from acounter-substrate CT side.

FIG. 3 is a cross-sectional view schematically showing a structure ofthe liquid crystal display panel PNL, which includes pixels PX1 to PX3as shown in FIG. 2.

FIG. 4 is a cross-sectional view schematically showing a structure ofthe liquid crystal display device including the liquid crystal displaypanel PNL and a cover member CG.

FIG. 5 is a view schematically showing a correlation between thedirection of a first absorption axis AB1 of a first polarizer PL1, thedirection of initial alignment of liquid crystal molecules LM, thedirection of a second absorption axis AB2 of a second polarizer PL2, andthe direction of a third absorption axis AB3 of polarized sunglasses.

FIG. 6 is a cross-sectional view schematically showing another structureof the liquid crystal display device including the liquid crystaldisplay panel PNL and the cover member CG.

DETAILED DESCRIPTION

In general, according to one embodiment, a liquid crystal display deviceincludes: an array substrate; a counter-substrate located opposite tothe array substrate; a negative liquid crystal layer including liquidcrystal molecules and held between the array substrate and thecounter-substrate; a retardation film attached to a surface of the arraysubstrate; a first polarizer attached to the retardation film and havinga first absorption axis; a second polarizer attached to a surface of thecounter-substrate, and having a second absorption axis which is parallelto a direction of initial alignment of the liquid crystal molecules andperpendicular to the first absorption axis; a cover member locatedopposite to the second polarizer; and ultraviolet curing resin bondingthe second polarizer and the cover member to each other.

Embodiments will be described hereinafter with reference to theaccompanying drawings. It should be noted that they are disclosed asmere examples; and needless to say, if they are modified as appropriateby a person with ordinary skill in the art without changing the subjectmatter of the invention, such modifications fall within the scope of theinvention as long as they can be easily conceived by a person withordinary skill in the art. In addition, in some cases, in order to makethe description clearer, the widths, thicknesses, shapes, etc. of partsare schematically illustrated in the drawings, compared to the actualmodes. However, the schematic illustration is merely an example, andadds no limitations to the interpretation of the embodiments.Furthermore, in the specification and drawings, structural elements,which have functions identical or similar to the functions described inconnection with preceding drawings, are denoted by the same referencenumbers, respectively, as those described previously, and an overlappingdetailed description or descriptions thereof are omitted unlessotherwise necessary.

FIG. 1 is a view schematically showing an equivalent circuit and aconfiguration of a liquid crystal display panel PNL included in a liquidcrystal display device according to an embodiment.

To be more specific, the liquid crystal display panel PNL is of anactive matrix transmissive type, and comprises an array substrate AR, acounter-substrate CT located opposite to the array substrate AR and aliquid crystal layer LQ held between the array substrate AR and thecounter-substrate CT. The array substrate AR and the counter-substrateCT are attached to each other by a sealant SE, with a predetermined cellgap provided between the array substrate AR and the counter-substrateCT. In an example shown in FIG. 1, the sealant SE is formed in the shapeof a rectangular frame and in a manner of a closed loop. The liquidcrystal layer LQ is located within the region surrounded by the sealantSE and held between the array substrate AR and the counter-substrate CT.The liquid crystal display panel PNL includes an active area ACT fordisplaying an image, within the region surrounded by the sealant SE. Theactive area ACT is, for example, substantially rectangular, andcomprises a plurality of pixels PX arranged in a matrix. In an example,the active area ACT has short sides TSH substantially parallel to afirst direction X and long sides TLO substantially parallel to a seconddirection Y. It should be noted that the first direction X isperpendicular to the second direction Y. Also, the liquid crystal panelPNL (or the array substrate AR and the counter-substrate CT) are alsorectangularly formed, and has short sides LSH substantially parallel tothe first direction X and long sides LLO substantially parallel to thesecond direction Y.

In the active area ACT, the array substrate AR comprises a gate line Gextending in a direction parallel to the short sides TSH (i.e.,extending in the first direction X), a source line S extending in adirection parallel to the long sides TLO (i.e., extending in the seconddirection Y), a switching element SW electrically connected to the gateline G and the source line S in the pixel PX, respectively, and thepixel electrode PE connected to the switching element SW in the pixelPX, respectively, and a common electrode CE having a common potential.

Although a detailed structure of the liquid crystal display panel PNLwill be described later, the liquid crystal display panel PNL accordingto the embodiment is configured to adopt a mode in which a lateralelectric field is primarily applied, and the pixel electrode PE and thecommon electrode CE are both provided at the array substrate AR.

Signal supply sources necessary to drive the liquid crystal displaypanel PNL, which are a drive IC chip 2, a flexible printed circuit (FPC)substrate 3, etc., are provided in a peripheral area PRP located outwardof the active area ACT. In the example shown in FIG. 1, the drive ICchip 2 and the FPC substrate 3 are mounted on a mounting portion MT ofthe array substrate AR, which is located outward of a substrate endportion CTE of the counter-substrate CT. The peripheral area PRP is anarea surrounding the active area ACT, includes an area where the sealantSE is located, and is formed in the shape of a rectangular frame.

FIG. 2 is a schematic plan view showing a configuration example ofpixels in the array substrate AR as shown in FIG. 1, as viewed from acounter-substrate CT side. It should be noted that FIG. 2 shows only amain portion which needs to be referred to in explanations to be givenbelow.

The array substrate AR comprises gate lines G1 to G3, source lines S1 toS4, switching elements SW1 to SW6, the common electrode CE, pixelelectrodes PE1 to PE6, a first alignment film AL1, etc.

The gate lines G1 to G3 extend in substantially parallel with the firstdirection X. The source lines S1 to S4 extend in substantially parallelwith the second direction Y, and cross the gate lines G1 to G3. Itshould be noted that the gate lines G1 to G3 and the source lines S1 toS4 need not always to linearly extend, and they may be partially bent.The gate lines G1 to G3 and the source lines S1 to S4 define the pixelsPX1 to PX6. The gate lines G1 to G3 and the source lines S1 to S4 areformed of, for example, molybdenum, chromium, tungsten, aluminum,copper, titanium, nickel tantalum, silver or an alloy of any elementsselected from those elements; however, the materials of the gate linesand source lines are not limited to those elements; that is, they may beformed of another metal, another alloy or another laminate film.

The pixels PX1 to PX3 arranged in the first direction X are color pixelshaving different colors, and the pixels PX4 to PX6 are also color pixelshaving different colors. In an example, the pixels PX1 and PX4 arrangedin the second direction Y are color pixels having the same color, forexample, green (G) pixels. Also, the pixels PX2 and PX5 arranged in thesecond direction Y are color pixels having the same color, for example,blue (B) pixels. The pixels PX3 and PX6 arranged in the second directionY are color pixels having the same color, for example, red (R) pixels.

The pixel PX1 is defined by the gate lines G1 and G2 and the sourcelines S1 and S2; the pixel PX2 is defined by the gate lines G1 and G2and the source lines S2 and S3; and the pixel PX3 is defined by the gatelines G1 and G2 and the source lines S3 and S4. The pixels PX1 to PX3extend in a first extension direction D1 crossing the second direction Yat an acute angle in a clockwise direction. The source lines S1 to S4,each of which is located on both sides of an associated one of thepixels PX1 to PX3, extend in the first extension direction D1.

The pixel PX4 is defined by the gate lines G2 and G3 and the sourcelines S1 and S2; the pixel PX5 is defined by the gate lines G2 and G3and the source lines S2 and S3; and the pixel PX6 is defined by the gatelines G2 and G3 and the source lines S3 and S4. The pixels PX4 to PX6extend in a second extension direction D2 crossing the second directionY at an acute angle in a counterclockwise direction. The source lines S1to S4, each of which is located on both sides of an associated one ofthe pixels PX4 to PX6, extend in the second extension direction D2. Itshould be noted that angle 91 at which the second direction Y and thefirst extension direction D1 cross each other (i.e., the crossing angleθ1 thereof) is substantially equal to angle θ2 at which the seconddirection Y and the second extension direction D2 cross each other(i.e., the crossing angle θ2 thereof), and those crossing angles areeach, for example, approximately 5 to 15′.

The common electrode CE is provided on substantially the entire area ofthe array substrate AR and in common for the pixels PX1 to PX6. To bemore specific, the common electrode CE extend over the gate lines G1 toG3 in the second direction Y and over the source lines S1 to S4 in thefirst direction X, and provided for the pixels PX1 to PX6.

In the pixel PX1, the switching element SW1 and the pixel electrode PE1are provided. The switching element SW1 is electrically connected to thegate line G2 and the source line S1. The pixel electrode PE1 is locatedbetween the source lines S1 and S2, and electrically connected to theswitching element SW1. In the pixel PX2, the switching element SW2 andthe pixel electrode PE2 are provided. The switching element SW2 iselectrically connected to the gate line G2 and the source line S2. Thepixel electrode PE2 is located between the source lines S2 and S3, andelectrically connected to the switching element SW2. In the pixel PX3,the switching element SW3 and the pixel electrode PE3 are provided. Theswitching element SW3 is electrically connected to the gate line G2 andthe source line S3. The pixel electrode PE3 is located between thesource lines S3 and S4, and electrically connected to the switchingelement SW3.

Similarly, in the pixel PX4, the switching element SW4 electricallyconnected to the gate line G3 and the source line S1 and the pixelelectrode PE4 electrically connected to the switching element SW4 areprovided. In the pixel PX5, the switching element SW5 electricallyconnected to the gate line G3 and the source line S2 and the pixelelectrode PE5 electrically connected to the switching element SW5 areprovided. In the pixel PX6, the switching element SW6 electricallyconnected to the gate line G3 and the source line S3 and the pixelelectrode PE6 electrically connected to the switching element SW6 areprovided.

The switching elements SW1 to SW6 are, for example, thin-filmtransistors (TFTs). The switching elements SW1 to SW6 comprisesemiconductor layers formed of, for example, poly-silicon (p-Si),amorphous silicon (a-Si), organic semiconductors, oxide semiconductorsor the like.

The pixel electrodes PE1 to PE6 are located above the common electrodeCE. The pixel electrodes PE1 to PE3 are formed in the shape of islandsin accordance with the shapes of pixels extending in the first extensiondirection D1. Furthermore, the pixel electrodes PE1 to PE3 each includeat least one slit SLA extending in the first extension direction D1. Thepixel electrodes PE4 to PE6 are formed in the shape of islands inaccordance with the shapes of pixels extending in the second extensiondirection D2. Furthermore, the pixel electrodes PE4 to PE6 each includeat least one slit SLB extending in the second extension direction D2.The slits SLA and SLB each face the common electrode CE. In the exampleillustrated, the pixel electrodes PE1 to PE3 each include two slits SLA,and the pixel electrodes PE4 to PE6 each include two slits SLB. Thenumber of slits provided in each pixel electrode is not especiallylimited; that is, it may be set to one or three or more.

The first alignment film AL1 is subjected to an alignment treatment in adirection which crosses at an acute angle exceeding 45° the long axes ofthe slits SLA (the first extension direction D1 in the example shown inFIG. 2) and the long axes of the slits SLB (the second extensiondirection D2 in the example shown in FIG. 2). An alignment direction R1of the first alignment film AL1 is substantially parallel to the firstdirection X, and crosses the first extension direction D1 or the secondextension direction D2 at an angle of less than 90°, for example, anangle of 75 to 85°. That is, preferably, the angle between the firstextension direction D1 and the direction of initial alignment of liquidcrystal molecules LM should fall within the range of 45 to 90°, and morepreferably, it should fall within the range of 75 to 85°. Also,preferably, the angle between the first extension direction D1 and thedirection of initial alignment of the liquid crystal molecules LM shouldbe equal to that between the second extension direction D2 and thedirection of initial alignment of the liquid crystal molecules LM.

FIG. 3 is a cross-sectional view schematically showing a structure ofthe liquid crystal display panel PNL including the pixels PX1 to PX3 asshown in FIG. 2.

The liquid crystal display panel PNL comprises the array substrate AR,the counter-substrate CT and the liquid crystal layer LQ. Furthermore, afirst optical element OD1 and a second optical element OD2 are providedat an outer surface of the liquid crystal display panel PNL.

The array substrate AR comprises a first insulating substrate 10, afirst insulating film 11, the common electrode CE, a second insulatingfilm 12, the pixel electrodes PE1 to PE3, the first alignment film AL1,etc. The first insulating substrate 10 is formed of a material havinglight transmitting and electrical insulating properties, such as glassor resin.

The first insulating film 11 is provided above the first insulatingsubstrate 10. Furthermore, the gate lines, the source lines and theswitching elements, which are not shown in FIG. 3, are provided betweenthe first insulating substrate 10 and the first insulating film 11.

The common electrode CE is provided on the first insulating film 11.Also, the common electrode CE is formed of a transparent conductivematerial such as indium tin oxide (ITO) or indium zinc oxide (IZO). Thecommon electrode CE is covered by the second insulating film 12.

The pixel electrodes PE1 to PE3 are provided on the second insulatingfilm 12 and opposite to the common electrode CE. In each of the pixelelectrodes PE1 to PE3, the slits SLA are provided. The pixel electrodesPE1 to PE3 are each formed of a transparent conductive material such asITO or IZO.

The first alignment film AL1 covers the pixel electrodes PE1 to PE3, andis also provided on the second insulating film 12. Also, the firstalignment film AL1 is formed of a material exhibiting a horizontalalignment characteristic, and located on a surface of the arraysubstrate AR which contacts the liquid crystal layer LQ.

On the other hand, the counter-substrate CT comprises a secondinsulating substrate 20, a light shielding layer BM, color filters CF1,CF2 and CF3, an overcoat layer OC, a second alignment film AL2, etc. Thesecond insulating substrate 20 is formed of a material having lighttransmitting and electrical insulating properties, such as glass orresin.

The light shielding layer BM is provided on an inner surface of thesecond glass substrate 20 which is located opposite to the arraysubstrate AR. The light shielding layer BM is formed of a materialhaving a low light transmittance and a low reflectivity, i.e., a blackresin material or a metal material having a light-shieldingcharacteristic.

The color filters CF1 to CF3 are provided on an inner surface of thesecond insulating substrate 20. The color filter CF1 is formed of aresin material colored green. The color filter CF2 is formed of a resinmaterial colored blue. The color filter CF3 is formed of a resinmaterial colored red. It should be noted that another color filter maybe further added as a color filter having a color (for example, atransparent filter or a white filter) different from the colors of thecolor filters CF1 to CF3.

The overcoat layer OC covers the color filters CF1 to CF3. The overcoatlayer OC is formed of, for example, a transparent resin material.

The second alignment film AL2 covers the overcoat layer OC. The secondalignment film AL2 is formed of a material exhibiting a horizontalalignment characteristic, and located on the surface of thecounter-substrate CT which contacts the liquid crystal layer LQ. Thefirst alignment film AL1 and the second alignment film AL2 are subjectedto an alignment treatment for causing liquid crystal molecules of theliquid crystal layer LQ to be in an initial alignment. The alignmentdirection R1 of the first alignment film AL1, as shown in FIG. 2, isparallel to the first direction X. The alignment direction R2 of thesecond alignment film AL2 is parallel to and the same direction as thealignment direction R1. As the alignment treatment, for example, arubbing treatment, a photo-alignment treatment or the like is applied.

The liquid crystal layer LQ contains liquid crystal molecules LMenclosed between the first alignment film AL1 of the array substrate ARand the second alignment film AL2 of the counter-substrate CT. Theliquid crystal layer LQ is formed of a liquid crystal constituent whosedielectric anisotropy is negative. The liquid crystal molecules LMreceive alignment restraining forces from the first alignment film AL1and the second alignment film AL2, and are in an initial alignment suchthat they are located in substantially parallel with an interfacebetween the liquid crystal layer LQ and the first alignment film AL1 andan interface between the liquid crystal layer LQ and the secondalignment film AL2. In the example shown in FIG. 2, the direction ofinitial alignment of the liquid crystal molecules LM is parallel to thefirst direction X.

The first optical element OD1 is attached to a surface of the arraysubstrate AR. The first optical element OD1 includes a retardation filmRE and a first polarizer PL1. The second optical element OD2 is attachedto a surface of the counter-substrate CT, and includes a secondpolarizer PL2. The first optical element OD1 and the second opticalelement OD2 are not limited to those described with respect to the aboveembodiment, and may each include another function layer.

At part of the liquid crystal display panel PNL which is locatedopposite to the first optical element OD1, a backlight unit BL isprovided. As the backlight unit BL, various kinds of backlight units canbe applied. However, a detailed explanation of the structure of thebacklight unit BL will be omitted.

FIG. 4 is a cross-sectional view schematically showing a structure ofthe liquid crystal display device including the liquid crystal displaypanel PNL and a cover member CG.

The liquid crystal display device accommodates in a housing frame FRformed in the shape of a box, the backlight unit BL, the liquid crystaldisplay panel PNL, the retardation film RE and the first polarizer PL1of the first optical element OD1, the second polarizer PL2 of the secondoptical element OD2 and ultraviolet curing resin UC.

The cover member CG is located opposite to the counter-substrate CT ofthe liquid crystal display panel PNL. The cover member CG is formed ofglass, resin or the like, which has a light transmitting property. Thecover member CG is, for example, attached to the housing frame FR, andthus fixed thereto. In an example, the cover member CG comprises a lightshielding layer SH located opposite to the liquid crystal display panelPNL. The light shielding layer SH defines the active area ACT, and alsoshields from light an area located outward of the active area ACT.

The backlight unit BL is provided on an inner surface of a bottomportion of the housing frame FR. The liquid crystal display panel PNL islocated opposite to the backlight unit BL. The retardation film RE isattached to a surface ARa of the array substrate AR which is locatedopposite to the backlight unit BL. The first polarizer PL1 is attachedto the retardation film RE. The second polarizer PL2 is attached to asurface CTa of the counter-substrate CT which is located opposite to thecover member CG. The retardation film RE, the first polarizer PL1 andthe second polarizer PL2 are all provided in the entire active area ACT.

The ultraviolet curing resin UC bonds the second polarizer PL2 and thecover member CG to each other. The ultraviolet curing resin UC isprovided in the entire active area ACT. If a certain amount ofultraviolet curing resin UC which can be provided in the entire activearea ACT is applied, part of the ultraviolet curing resin UC spreads toan area located outward of the active area ACT. In the liquid crystaldisplay device of recent times, the area outward of the active area ACTtends to be set smaller, and it is therefore harder to apply ultravioletcuring resin UC only to a surface HF of the second polarizer PL2. Thus,in the example shown in FIG. 4, the ultraviolet curing resin UC is incontact with the surface HF and side surface LF of the second polarizerPL2. Furthermore, the ultraviolet curing resin UC is also in contactwith part of the surface CTa of the counter-substrate CT, which isexposed from the second polarizer PL2 to the outside thereof.

The retardation film RE is provided to, for example, compensate for aviewing angle of the liquid crystal display device. In general, aretardation film or retardation films RE are provided between the liquidcrystal display panel PNL and the first polarizer PL1 and/or between theliquid crystal display panel PNL and the second polarizer PL2. In theembodiment, the retardation film RE is provided only between the liquidcrystal display panel PNL and the first polarizer PL1. Thus, theretardation film RE is not in contact with the ultraviolet curing resinUC. It should be noted that the phase difference value of theretardation film RE and the direction of the phase lag axis of theretardation film RE are not especially limited, and can be selected asappropriate in accordance with the function of the liquid crystaldisplay panel PNL and a first absorption axis AB1 of the first polarizerPL1. In an example, the retardation film RE is combined with the firstpolarizer PL1 into a single body in advance, and it is set that thephase lag axis of the retardation film RE and the first absorption axisAB1 cross each other at a predetermined angle.

Next, use of the liquid crystal display device according to theembodiment will be explained by referring to an example shown in FIG. 5.

FIG. 5 is a view schematically showing a correlation between thedirection of the first absorption axis AB1 of the first polarizer PL1,the direction of initial alignment of the liquid crystal molecules LM,the direction of a second absorption axis AB2 of the second polarizerPL2, and the direction of a third absorption axis AB3 of polarizedsunglasses SG.

The liquid crystal display device is held by a user such that the activearea ACT is located in portrait orientation as viewed from the user.Also, the user views the active area ACT from the front. That is, theactive area ACT is located such that its short sides TSH aresubstantially parallel to a horizontal direction, and its long sides TLOare substantially parallel to a vertical direction. Similarly, the firstpolarizer PL1, the liquid crystal display panel PNL, the secondpolarizer PL2 and the cover member CG all have short sides substantiallyparallel to the horizontal direction and long sides substantiallyparallel to the vertical direction. It should be noted that as shown inFIG. 1, in the embodiment, the gate line G extends in substantiallyparallel with the short sides TSH of the active area ACT. Also, thesource line S extends in substantially parallel with the long sides TLOof the active area ACT. Therefore, when the liquid crystal displaydevice is used, the horizontal direction corresponds to the direction ofextension of the gate line G (or the first direction X), and thevertical direction corresponds to the direction of extension of thesource line S (or the second direction Y). It should be noted that anarrow drawn by a broken line in such a way to penetrate the firstpolarizer PL1, the liquid crystal display panel PNL, the secondpolarizer PL2 and the cover member CG indicates the path of light LTemitted from the liquid crystal display device and visibly recognized bythe user.

The first absorption axis AB1 of the first polarizer PL1 is parallel tothe second direction Y. The direction of initial alignment of the liquidcrystal molecules LM is parallel to the first direction X. The secondabsorption axis AB2 of the second polarizer PL2 is perpendicular to thefirst absorption axis AB1 and parallel to the first direction X. Thatis, the first polarizer PL1 and the second polarizer PL2 are disposed ina cross Nicol arrangement. Furthermore, the second absorption axis AB2is parallel to the short sides TSH of the active area ACT and alsoparallel to the direction of extension of the gate line G. The directionof initial alignment of the liquid crystal molecules LM is parallel tothe second absorption axis AB2.

On the other hand, the third absorption axis AB3 of the polarizedsunglasses SG is parallel to the horizontal direction (or the firstdirection X) in order to block reflected sunlight from the surface ofwater or the like. Light LT emitted to the outside of the liquid crystaldisplay device after passing through the cover member CG is a linearpolarization substantially perpendicular to the second absorption axisAB2. Therefore, the polarization direction of the above emitted light LTis substantially perpendicular to the third absorption axis AB3 of thepolarized sunglasses SG. Thus, the light LT emitted from the liquidcrystal display device is visually recognized through the polarizedsunglass SG.

Then, the operation of the liquid crystal display device having theabove structure will be explained.

At an OFF time when a voltage which makes a potential difference betweenthe pixel electrode PE and the common electrode CE is not applied, novoltage is applied to the liquid crystal layer LQ. That is, an electricfield is not generated between the pixel electrode PE and the commonelectrode CE. Thus, as indicated by a solid line in FIG. 2, the liquidcrystal molecules LM in the liquid crystal layer LQ are initiallyaligned in the first direction X in an X-Y plane by alignmentrestriction forces of the first alignment film AL1 and the secondalignment film AL2.

At the OFF time, part of backlight from the backlight unit BL istransmitted through the first polarizer PL1 and incident on the liquidcrystal display panel PNL. At this time, the light incident on theliquid crystal display panel PNL is a linear polarization perpendicularto, for example, the first absorption axis AB1 of the first polarizerPL1. Such linear polarization hardly changes when the liner polarizationis transmitted through the liquid crystal display panel PNL at the OFFtime. Thus, most of the linear polarization transmitted through theliquid crystal display panel PNL is absorbed by the second polarizer PL2(black display).

Conversely, at an ON time when a voltage which makes a potentialdifference between the pixel electrode PE and the common electrode CE isapplied, a voltage is applied to the liquid crystal layer LQ. That is, alateral electric field (or a fringing field) substantially parallel tothe X-Y plane is generated between the pixel electrode PE and the commonelectrode CE. Thus, as indicated by a broken line in FIG. 2, in the X-Yplane, the liquid crystal molecules LM are aligned in directionsdifferent from the direction of the initial alignment. If a negativeliquid crystal material is applied, for example, liquid crystalmolecules LM of the pixel PX3 are rotated in a counter-clock wisedirection so that they are aligned in a direction substantiallyperpendicular to the fringing field in the X-Y plane, and liquid crystalmolecules LM of the pixel PX6 are rotated in a clockwise direction sothat they are aligned in the direction substantially perpendicular tothe fringing field in the X-Y plane. At this time, the liquid crystalmolecules LM are aligned in a direction according to the magnitude ofthe electric field.

At the ON time, a linear polarization perpendicular to the firstabsorption axis AB1 of the first polarizer PL1 is incident on the liquidcrystal display panel PNL, and varies in accordance with the alignmentstate of liquid crystal molecules LM when the linear polarization passesthrough the liquid crystal layer LQ. Thus, at the ON time, at least partof light passing through the liquid crystal layer LQ is transmittedthrough the second polarizer PL2 (white display).

By virtue of the above structure, a normally-black mode is achieved.

In the liquid crystal display device having the above structureexplained with reference to FIG. 2, pixels adjacent to each other in thesecond direction Y (for example, the pixels PX1 and PX4) take on thesame color, and include respective pixel electrodes which are providedwith slits extending in different directions. Thus, liquid crystalmolecules LM of the pixels adjacent to each other in the seconddirection Y are aligned in different directions at the ON time. That is,the pixels adjacent to each other in the second direction Y and takingon the same color form two kinds of pseudo domains. In such a liquidcrystal display device, odd-numbered rows of pixels and even-numberedrows of pixels in the second direction Y mutually compensate for theviewing angle. Thus, the viewing angle can be widened.

It should be noted that in the embodiment, the retardation film RElocated between the array substrate AR and the first polarizer PL1functions as a viewing-angle compensation film. To be more specific, inthe black display at the OFF time or in the white display at the ONtime, in the cases where the liquid crystal display device is viewedfrom the front and where it is viewed obliquely, the retardation film REappropriately gives a phase difference to light transmitted through theliquid crystal display panel PNL, to thereby compensate for thedifference in displayed state between the above cases.

As described above, according to the embodiment, the retardation film REis attached to the surface of the array substrate AR, and the secondpolarizer PL2 attached to the surface of the counter-substrate CT isalso attached to the cover member CG by the ultraviolet curing resin UC.Thus, from time when an uncured ultraviolet curing resin material isapplied to time when it is cured as the ultraviolet curing resin UC,there is no possibility that the retardation film RE will contact theuncured ultraviolet curing resin material. It is therefore possible toprevent the retardation film RE from being damaged or changed in qualityby the ultraviolet curing resin material. Thereby, it is possible toprovide a liquid crystal display device which can restrict lowering ofthe reliability. It should be noted that the inventor did a temperaturetest to confirm if the liquid crystal display device according to theembodiment passes 250 cycles of rapid temperature changing of −40 to+85° C., and confirmed that the retardation film RE was not changed inquality or broken. Furthermore, the ultraviolet curing resin UC is incontact with not only the surface HF and side surface LF of the secondpolarizer PL2, but part of the surface CTa of the counter-substrate CT.That is, the ultraviolet curing resin UC contacts a lot of surfaces ofthe second polarizer PL2 and the counter-substrate CT, and can thusobtain satisfactory bonding strengths for the second polarizer PL2 andthe counter-substrate CT.

Also, according to the embodiment, since the retardation film RE doesnot contact the uncured ultraviolet curing resin material, it is notnecessary to use a retardation film RE having a high chemicalresistance. Therefore, it is possible to more freely select the materialof the retardation film RE. Also, the material of the ultraviolet curingresin UC can be selected without considering the chemical resistance ofthe retardation film RE. It is therefore possible to more freely selectthe material of the ultraviolet curing resin UC. Since the material ofthe retardation film RE and that of the ultraviolet curing resin UC canbe more freely selected, the cost of the liquid crystal display devicecan be reduced.

In addition, the third absorption axis AB3 of the polarized sunglassesSG is substantially parallel to the second absorption axis AB2 of thesecond polarizer PL2. Thus, according to the embodiment, even if wearingthe polarized sunglasses SG, the user can visibly recognize an imagedisplayed on the liquid crystal display device. That is, it is possibleto provide a liquid crystal display device supporting use of polarizedsunglasses.

Next, a modification of the embodiment will be explained.

FIG. 6 is a cross-sectional view schematically showing another structureof the liquid crystal display device including the liquid crystaldisplay panel PNL and the cover member CG.

In the modification, a cover member CG includes a touch sensor TP on asurface located opposite to the liquid crystal display panel PNL. Inthis regard, the modification is different from a structure of theembodiment as shown in FIG. 4. The other structure of the modificationis the same as the other structure of the embodiment as shown in FIG. 4.Thus, the elements of the other structure of the modification aredenoted by the same reference numbers as in the other structure of theembodiment as shown in FIG. 4, and their explanations will be omitted.

With respect to the above point, in the modification, the cover memberCG comprises a support member SP and the touch sensor TP. The supportmember SP is formed of glass, resin or the like, which has a lighttransmitting property. The touch sensor TP is provided on a surface ofthe support member SP which is located opposite to the liquid crystaldisplay panel PNL. The cover member CG is attached to a second polarizerPL2 by ultraviolet curing resin UC.

In such a modification also, the same advantage as in the aboveembodiment can be obtained.

It should be noted that with respect to the embodiment, it is explainedabove by way of example that the common electrode CE is provided as afirst electrode, and the pixel electrode PE is provided as a secondelectrode including at least one slit; however, the pixel electrode PEand the common electrode CE may be disposed as the first electrode andthe second electrode including the slit, respectively.

As explained above, according to the embodiment, it is possible toprovide a liquid crystal display device which can restrict lowering ofthe reliability.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms; furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A liquid crystal display device comprising: abacklight unit; an array substrate including source lines arrayed in afirst direction at an interval, gate lines arrayed in a second directioncrossing the first direction at an interval, an insulating film having afirst surface and a second surface opposed to the first surface, acommon electrode which is in contact with the first surface of theinsulating film, a first pixel electrode which is in contact with thesecond surface of the insulating film, a second pixel electrode which isin contact with the second surface of the insulating film, and a firstalignment film which is in contact with the first pixel electrode andthe second pixel electrode; a counter-substrate including a secondalignment film; a cover member; a liquid crystal layer between the arraysubstrate and the counter-substrate; a first polarizer which is locatedon one of the backlight unit's side and the cover member's side; and asecond polarizer which is located on the other of the cover member'sside and the backlight unit's side, wherein the liquid crystal layerincludes negative liquid crystal molecules, an absorption axis of thesecond polarizer, a direction of initial alignment of the negativeliquid crystal molecules, and a photo-alignment treatment direction ofthe second alignment film are substantially parallel, an absorption axisof the first polarizer is perpendicular to the absorption axis of thesecond polarizer, the first pixel electrode and the second pixelelectrode overlap the common electrode, the second pixel electrode islocated adjacent to the first pixel electrode in the second direction,the first pixel electrode has a first slit, a long axis of the firstslit extends in a first extension direction crossing the photo-alignmenttreatment direction, the second pixel electrode has a second slit, thefirst slit is formed inside of an outer edge of the first pixelelectrode and exposes the second surface of the insulating film, a longaxis of the second slit extends in a second extension directiondifferent from the first extension direction, the first extensiondirection crosses the second direction at an acute angle in a clockwisedirection, and is different from the first direction and the seconddirection, the second extension direction crosses the second directionat an acute angle in a counterclockwise direction, and is different fromthe first direction and the second direction, a crossing angle of theabsorption axis of the first polarizer and the first extensiondirection, and a crossing angle of the absorption axis of the firstpolarizer and the second extension direction, are each approximately 5°to 15°, and the first alignment film is in contact with the secondsurface of the insulating film in the first slit and the second slit. 2.The liquid crystal display device of claim 1, wherein an angle betweenthe first extension direction and the photo-alignment treatmentdirection is greater than 45° and less than 90°.
 3. The liquid crystaldisplay device of claim 1, wherein an angle between the first extensiondirection and the photo-alignment treatment direction is greater than75° and less than 85°.
 4. The liquid crystal display device of claim 3,wherein the first direction is substantially parallel to the absorptionaxis of the second polarizer, the direction of initial alignment, andthe photo-alignment treatment direction.
 5. The liquid crystal displaydevice of claim 4, further comprising an ultraviolet curing resinbonding the second polarizer and the cover member, and a retardationfilm between the array substrate and the first polarizer, wherein theretardation film is not between the cover member and thecounter-substrate.
 6. The liquid crystal display device of claim 5,wherein the first polarizer is between the backlight unit and the arraysubstrate, and the second polarizer is between the counter-substrate andthe cover member.
 7. The liquid crystal display device of claim 6,wherein the ultraviolet curing resin is in contact with part of thecounter-substrate, which is exposed from the second polarizer to anoutside thereof, and the ultraviolet curing resin is in contact with aside surface of the second polarizer.
 8. The liquid crystal displaydevice of claim 5, wherein the cover member comprises a touch sensorlocated on the ultraviolet curing resin.
 9. The liquid crystal displaydevice of claim 4, wherein the gate lines extend in the first direction,and the absorption axis of the second polarizer is parallel to shortsides of an active area for use in displaying an image, and is parallelto the first direction.
 10. The liquid crystal display device of claim9, wherein the first pixel electrode and the second pixel electrode aredisposed in adjacent pixels which take on the same color, and form twokinds of pseudo domains.
 11. The liquid crystal display device of claim10, wherein the gate lines have a gate line, the gate line iselectrically connected to the first pixel electrode, and a part of thesecond pixel electrode overlaps the gate line.
 12. The liquid crystaldisplay device of claim 1, wherein the first pixel electrode and thesecond pixel electrode are disposed in adjacent pixels which take on thesame color, and form two kinds of pseudo domains.